Not Applicable
Not Applicable
Field of the Invention
The present invention relates to a method of improving the permeability of an earth formation zone surrounding a wellbore formed in the earth formation. In the practice of producing hydrocarbon fluid from an earth formation via a wellbore to a production facility at surface, a perforated casing or liner is generally installed in the wellbore. The hydrocarbon fluid flows via the pores of the formation towards the casing or liner and via the perforations thereof into the wellbore.
A problem frequently encountered is that the permeability of the earth formation is relatively low resulting in reduced production capacity of the wellbore. One cause of such reduced permeability is the presence of formation illite in the pores-. Formation illite is a clay mineral which partially occupies the interstices between the rock particles. The presence of illite in the form of needles or platelets significantly reduces the ability of hydrocarbon fluid to flow through the pores.
It is an object of the invention to provide a method of improving the permeability of an earth formation zone surrounding a wellbore formed in the earth formation.
In accordance with the invention there is provided a method of improving the permeability of an earth formation zone surrounding a wellbore formed in the earth formation, the method comprising
pumping a selected liquid via the wellbore into said earth formation zone so as to create a body of liquid extending into the wellbore and into the pores of said zone;
lowering a shock wave generator into the body of liquid in the wellbore; and
inducing the shock wave generator to generate a shock wave in the body of liquid.
It is thereby achieved that the shock wave travels through the pores of the formation where the body of liquid is present and thereby destroys the illite particles present in the pores.
The invention will be described further in more detail and by way of example with reference to the accompanying drawings in which